The present invention relates to a ventilator structure of the type that is normally disposed in the foundation of a dwelling or other building structure. More particularly, the present invention relates to a ventilator with automatic, temperature responsive means for opening and closing the ventilator to the passage of air therethrough.
A number of automatic, temperature responsive ventilators are known, including French Pat. No. 1,377,998 and those disclosed in the following U.S. Pat. Nos.:
______________________________________ U.S. Pat. No. Inventive Entity ______________________________________ 4,754,696 Sarazen et al 4,715,532 Sarazen, Jr. et al 4,493,456 Sarazen, Jr. et al 4,328,927 McSwain 4,290,554 Hensley 4,274,330 Witten et al 4,243,175 McSwain 4,231,514 McSwain 4,210,279 McSwain 4,208,0l0 Beam, Jr. et al 4,175,480 Beam, Jr. et al 4,151,952 Edwards 3,528,606 Witten 3,436,0l6 Edwards 3,368,756 Edwards 3,195,441 Hedrick 3,068,776 Day 3,027,090 Zerhan, Jr. 2,975,975 Weber 2,814,977 Noll 2,551,965 Petersen et al 2,241,108 Akers 2,216,873 Browne 2,187,767 Akers 2,117,529 Wile et al 1,358,193 Fulton 1,335,929 Allen 302,215 Tucker ______________________________________
A bimetallic element provides a temperature operative mechanism to open and close the shutter elements of many of these vents. For example, a relatively wide coil is used in the Edwards '016 vent and in the Noll device. Sarazen et al '696 uses a narrower coil than the Edwards '016 vent. A spiral spring provides the temperature responsive element in the Edwards '756 vent. An elongated helical spring is used in an embodiment of the McSwain '514 device, in the Edwards '952 device, and in the McSwain '175 device.
The bimetallic element has been disposed at a number of different locations relative to the housing which defines the air passageway. In devices such as shown in Witten '606, a coil spring is located in an enclosed box on the exterior of one sidewall which defines the air flow passageway. This arrangement requires the size of the installation opening to be increased merely to accommodate the box. In the Edwards '016 device, the Beam, Jr. et al '480 device, and the Sarazen. Jr. et al '456 device, the coil spring is located in the air flow passageway of the ventilator in a central opening in one of the louvers. In the Sarazen, Jr.et al '696 device, the spring is located in the air flow passageway in an opening at one end of a louver. These arrangements require clearance space around the spring to enable the spring to expand, and this space admits air drafts and light through the louver and is aesthetically undesirable. Ventilators with relatively thick sidewalls such as McSwain '279, house the thermally responsive spring in an opening shown at 28 in FIG. 2 provided in the sidewall of the ventilator housing. This arrangement requires a compromise between the thickness of the sidewall and the depth of the spring. A sidewall that is too thick wastes material and/or destroys the symmetry of the vent. A spring that is too thin limits either the size and number of louvers which can be driven or limits the range of the louvers' movement.
A number of different ways of operatively connecting the bimetallic elements to propel movement of the louvers have been used. The outer end of the thermally responsive coil spring is secured to one of the louvers in ventilators such as Sarazen, Jr. et al '456 (middle of louver) and Sarazen et al '696 (end of louver). In the Sarazen, Jr. et al '456 device, the inner end of the coil spring is fixed to a stationary support rod. In the Sarazen, Jr. et al '696 device, a setting plug 35 extends through an opening in the sidewall to hold the inner end of the coil spring against rotation. Edwards '016 has a single, centrally disposed rod 36 secured to L-shaped lugs 34, which in turn are attached to louvers 26 for simultaneous movement with rod 36, and one louver is attached to the outer end of spring 40. In the Beam, Jr. et al '480 device, the inner end of the coil spring is attached to a stationary support rod for the louver, and the outer end attached directly to the surface of the louver. The McSwain '927 device connects the outer end of the coil spring to the louver and the inner end of the coil spring has a projection that extends outwardly and is received and nonrotatably held in an opening provided in the sidewall of the housing that defines the air flow passageway. The projection of the inner end of the spring provides an axis of rotation for the louver as the projection extends through an opening in a flange that extends from the louver blade. In the McSwain '279 device, the inner end of the coil spring is secured to the axis of rotation of one of the shutter elements, and the outer end of the coil spring is held in a slot formed in the boundary of an opening provided in the sidewall of the housing that defines the air flow passageway. Thus, in this McSwain '927 device and the McSwain '279 device, the inner end of the spring must carry the weight of the louver blade.
Moreover, devices which attach the spring to the louver element itself generally require about a 60.degree. range of movement of the spring between the open and closed positions of the louvers. A smaller range of spring movement to effect the same range of louver movement is desirable. This has been accomplished by attaching the spring to a linkage element which uses leverage to drive the louvers with a shorter range of spring movement. For example, Hensley '554 holds the inner end of the coil spring, which is mounted in a box on the exterior of the housing, in a bifurcated stud 43 extending outwardly through the sidewall of the housing. The outer end of the coil spring extends loosely through a slot 45 in an extension 35' of an actuator bar 35, which connects the three louvers for simultaneous movement. The Witten '606 device holds the inner end of spring 60 stationary by mounting it in a bolt 61, and attaches the outer end of spring 60 to a linkage in the form of connecting member 53 disposed outside of the housing which defines the air passageway. Hensley ' 554 disposes the bar inside the air passageway, while Witten '606 disposes the connecting member in the box on the outside of the air passageway housing.
Substantially complete blockage of air and light when the louvers are in the closed position is desireable. This is accomplished in arrangements such as shown in U.S. Pat. No. 3,202,082 to Viehmann (not a temperature actuating ventilator), in which each louver has oppositely disposed free edges configured to contact the overlapping free edge of the adjacent louver. Moreover, the lowermost louver has a lower free edge that overlaps and contacts an upwardly projecting member of the frame which surrounds the louvers. However, to allow free louver movement between the closed and open position, the upper free edge of the uppermost louver is free in the closed position, and thus a clearance space exists between it and the frame. This space may produce an undesirable whistle in the wind.
Adequate clearance between the housing and the uppermost and lowermost louvers must be provided. However, in vents in which the housing, louvers, and connecting elements are fabricated from molded plastic, clearance tolerances for the space between the top and bottom louvers must be large enough to accommodate warpage of the molded plastic elements. Thus, in the Hensley '554 vent for example, which is fabricated of molded plastic, when the louvers are in the closed position the upper free edge of the uppermost louver and the lower free edge of the lowermost louver do not directly contact the top and bottom surfaces defining the air passageway and have a generous clearance space between themselves and the passageway walls.
Because these ventilators are typically installed in the walls of foundations, the air flowing against them and through them deposits dirt and dust on them and in them. Unless this dust and dirt is removed, the airflow eventually carries both into the dwelling. Most ventilators cannot be cleaned without being removed from the foundation and/or disassembled at least in part. With most ventilators, removal and/or even partial disassembly is either difficult and/or impossible without damaging the ventilator or the skillful use of tools. With those that can be disassembled, one cannot always gain unimpeded access to the louvers for cleaning, much less remove them for cleaning.